In the bowels of the brand new Jose Alvalade stadium on a hot night in August 2003, Sir Alex Ferguson was finishing his pre-match talk to his Manchester United players about what to expect in their pre-season friendly against Sporting CP.

At the end of his speech, Ferguson nonchalantly added, "Oh, lads, and one final thing: They have a talented young winger. Look out for him, OK? He's strong and agile. He's quite good."

"That was it," former United defender Mark Lynch recalled; Lynch would come on in the second half. "No big warning; no time spent on him; just a few words; almost as if Sir Alex wanted to shock us."

The "talented young winger" was Cristiano Ronaldo. Over the next 90 minutes, he would have the game of his life, earning himself a move to Manchester United within a matter of days.

Wearing the No. 28 on his back, braces on his teeth and with recently added blond highlights in his hair, a raw and almost gawky 18-year-old Ronaldo tormented United with his pace and skill.

"It was an incredible performance to watch that night," former United defender and French international Mikael Silvestre said. "This kid nobody knew tore us apart for the whole game. No one could get near him; he was amazing. At the start, no one had even heard of Ronaldo, but by the end, everyone knew about him."

The Manchester United players might have been taken by surprise, but the scouts and sporting directors of most of Europe's leading clubs had known about Ronaldo for several years.

Soon after he arrived in Lisbon, Portugal, at the age of 12, glowing reports began emanating about the rare young talent with the familiar and famous surname. Fanciful stories would spread across Europe about the boy who had it all: pace, power, balance and the ability to glide past players.

By the summer of 2002, an impatient 17-year-old Ronaldo had enlisted a new agent, Jorge Mendes, to help him find a move away from Sporting.

There were plenty of options. A long list of clubs, including Valencia, Liverpool, Juventus, Inter Milan, Parma and Barcelona had all been monitoring Ronaldo, and many were preparing bids.

Early in 2003, Ronaldo seemed destined for Arsenal. He even travelled to north London to meet Arsene manager Wenger and have a tour of the club's training ground, but the clubs ultimately could not agree upon a deal. It left Wenger to lament in 2014 to Huawei (via Goal.com's Liam Twomey), "My biggest regret? I was so close to signing Cristiano Ronaldo. [...] That, of course, still hurts today."

In June 2002, Carlos Queiroz, who had managed Portugal, South Africa and Sporting CP, arrived at Old Trafford to become Ferguson's new assistant. As Ferguson recalled in his autobiography, Queiroz immediately told him: "There's a young boy at Sporting, and we need to keep an eye on him.

"Carlos said we need to act because this boy was special, and so we sent Jim Ryan to watch him train as part of our reciprocal deal. Jim returned and said, 'Wow, I've seen a player. I think he's a winger, but he's been playing centre-forward in the youth team. I wouldn't be waiting too long. At 17, someone will gamble.'"

Manchester United were already in the process of agreeing to an informal alliance with Sporting, ostensibly to share advice on scouting, training and player development. The real intention was to give United first refusal on the talent from Sporting's youth teams, including access to the ultimate prize: Cristiano Ronaldo.

As a part of this arrangement, United agreed to play Sporting CP in a pre-season friendly to open Sporting's new stadium in August 2003, which had been built ahead of staging several games in the following year's European Championship.

United arrived in the Portuguese capital directly from New York the night before the game, having already been away on a tour of the United States for the previous three weeks.

"The truth is, we were all ready to go home, but we had one more game in Portugal," Lynch said. "We were all tired, and a lot of us had jet lag after crossing the Atlantic, and I think we were up the day of the game walking around the lobby of the very nice hotel we were staying in at something like 4 a.m."

Silvestre adds: "None of us were in the mood for the game. The attitude was, 'Let's get this over with and get home.' For Sporting, it was a big deal, but for us, it was just another friendly."

Silvestre started the game in the centre of the United defence alongside Rio Ferdinand. Within minutes, their attention was drawn to the teenager on the left wing desperate to impress.

"I had never heard of Ronaldo, but as soon as he got the ball, he was beating players with ease on the left or the right," Silvestre said. "He was so quick and skillful; we were all a bit shocked. I remember thinking thank God I was playing in the centre and not at full-back."

Former United defender Danny Pugh, now at Port Vale, started that night on the bench alongside fellow substitutes Lynch, Ruud van Nistelrooy, Phil Neville and Darren Fletcher, as well as Ryan Giggs and club captain Roy Keane, who had been rested.

"The first time he picked up the ball, he did a bit of skill, beat a player and all of us on the bench sat up together and took notice," Pugh said. "Someone said, 'This must be the lad the manager was talking about.'

"He was there to put on a show. Every time he got the ball, he wanted to do something, he had so much belief. He was still quite slight then, but he had so much natural talent. It was the way he carried the ball and skipped past players."

United had harboured an active interest in Ronaldo for a year, and it seemed clear he was aware the match offered him a chance to banish any doubts they might have.

"After about 15 minutes, you could just look down the bench and most of us, including Roy Keane and Ryan Giggs, were shaking our heads, with our mouths wide open, not quite believing what we were watching," Lynch recalled.

"An 18-year-old lad was taking our defence apart. We were all just muttering, 'He's unbelievable.' He was showboating, of course, but he was doing it really well."

While the United bench enjoyed the evening's entertainment, John O'Shea, playing at right-back and coming up directly against Ronaldo, was most definitely not.

"He tore John to shreds in that first half," Lynch said. "I can remember the gaffer shouting, 'Any chance you could get a bit tighter to him, John?' Sheasy just turned to us, shaking his head, and said, 'Er, that's easier said than done!'"

In his book, My Autobiography, Ferguson wrote about "a look of pain and bewilderment creeping across [O'Shea's] face" during the first half. At half-time, Roy Keane suggested in his book, The Second Half, O'Shea needed to see the club doctor for dizziness, while Rio Ferdinand, also in his book, Rio: My Story, said O'Shea was given an oxygen mask. The players B/R spoke with had no recollection of O'Shea requiring any medical attention in the dressing room, however.

"No, no, that is just banter from Roy and Rio, just making fun of John," Silvestre said. "He had to sit down and catch his breath, but he didn't need to see a doctor."

Throughout the first half, Ferguson wrote, players next to him on the bench were saying, "'Bloody hell, Boss, he's some player, him.' I said: 'It's all right. I've got him sorted.'"

In his book, Ferguson wrote that he told his kit man, Albert Morgan, 'Get up to that directors' box and get [United chief executive] Peter Kenyon down at half-time.' I told Peter, 'We're not leaving this ground until we've got that boy signed.'

Peter asked: 'Is he that good?'

'John O'Shea has ended up with a migraine!' I said. 'Get him signed.'"

Eight minutes into the second half, O'Shea was spared any more punishment, as Lynch replaced him at right back.

"I had noticed in the warm-up that the pitch was one of the worst I had ever seen; it was in a terrible state," Lynch remembered. "You just couldn't play on it. It was very difficult to even plant your foot to kick the ball, because the pitch would give way beneath you and the ball was just bobbling everywhere."

"Ronaldo had the ball stuck to his foot, dancing around all of us. The thought occurred to all us that if he could play this well on this terrible pitch, just what will he be capable of on a decent surface? It was frightening to consider it.

"Ronaldo struck fear into me. You had to watch him so carefully, and at one point, he put the ball through my legs, and all I could do was bring him down. They scored their second goal from that free-kick. He was unplayable that night."

Lynch was offered a respite when Ronaldo switched to the right wing, where the task of stopping him fell to Pugh, who had come on for Kieran Richardson for the last half-hour.

"When he ran at me, I thought, 'Bloody hell, what am I am going to do?'" Pugh said. "He could go left or right and had every trick imaginable. He was strong and could manipulate the ball so well."

Sporting finished with a 3-1 win, but that paled in importance to the impression Ronaldo had made. For the first time many of those B/R spoke with could remember, United players proceeded to badger Ferguson to sign an opposing player.

"Phil Neville came straight off the pitch and walked up to Sir Alex in the dressing room," Silvestre said. "'Boss, you have to sign him, you just have to! Sir Alex just said, 'OK, OK, don't worry, we are going to get it sorted.'"

Showered and dressed in their club blazers, United players were forced to sit on the coach outside the stadium for what they noticed was an unusually long time. Inside, Ferguson and Kenyon were trying to negotiate a deal to sign Ronaldo. Ferguson had not been joking about not leaving until it was done.

Not only had Ronaldo's performance lent an urgency to the negotiations, but so, too, did the presence of some competing clubs that evening. Barcelona football director Txiki Begiristain had been inside the stadium that night to scout Ronaldo, while Carlos Queiroz, who had just been appointed Real Madrid manager, had instructed his sporting director, Jorge Valdano, to quickly sign the player.

Originally, United had planned to sign Ronaldo and then loan him back to Sporting for a year. Now they wanted him in Manchester immediately. After the game, they agreed to pay Sporting £12.24 million, a British record for a teenager.

In a small room inside the stadium after the game, Ferguson spoke to Ronaldo and his agent, Jorge Mendes. "We told him how much we would love to sign him for United," Ferguson wrote in his book. "I said, 'You won't play every week, I'm telling you that now, but you'll become a first-team player. There's no doubt in my mind about that. ... It'll take time for you to adjust. We'll look after you.'"

Meanwhile, the players waited.

"We were sitting on the coach for more than an hour, so the rumours started among us that the manager was actually signing him," Silvestre recalled. "Finally, Sir Alex got on the coach, and we were all saying, 'Have we got him?' The manager just smiled."

It was the smile of a man who had captured the best young player in the world. A few days later, Ronaldo and his family, accompanied by Mendes, were on a private jet to Manchester to sign his United contract.

On a tour of United's Carrington training ground, Ronaldo, wearing a memorably bright jumper, met his new team-mates.

"Ronaldo bumped into John O'Shea, and John joked, 'You owe me for getting you this move!'," Pugh said. "It was translated for him, and Ronaldo began laughing a lot."

United players remember a shy teenager off the pitch, but Ronaldo became a confident character as soon as he joined them for training.

"He did not have a nervous bone in his body," Lynch said. "He walked into the club and onto the training pitch like he belonged here. I have seen many young lads get nervous about playing with superstars, but he already thought he was one himself. He carried himself so well and just took it all in stride."

Ten days after playing for Sporting CP against United, Ronaldo would make his debut at Old Trafford on the opening day of the new Premier League season.

Wearing the now-iconic No. 7 on his back for the first time, Ronaldo came on as a substitute for Nicky Butt with a half-hour remaining. He picked up where he had left off in Portugal with a performance full of skill, pace and a flurry of indulgent step-overs, as United beat Bolton 4-0.

In the stands, veteran Manchester Evening News reporter Stuart Mathieson remembers Tom Tyrrell, a presence in the Old Trafford press box for more than four decades, saying, "I've not seen a debut like that since George Best."

To Silvestre, who started against Bolton, "It was Ronaldo trying to impress everyone in a hurry again, holding onto the ball a lot, but the crowd loved it and were on their feet."

It also was the first of Ronaldo's 292 appearances for Manchester United, over which time he would score 118 goals and win three Premier League titles, an FA Cup, two League Cups, the Champions League, and the Club World Cup. He then joined Real Madrid in 2009 for a world-record £80 million and went on to enjoy even greater success in the Spanish capital.

A couple of months after his United debut, Ronaldo was sitting in a Jacuzzi next to Silvestre after a training session at Carrington.

"I told him: 'You know, I think you can be the world's best player, and one day soon you will win the Ballon d'Or,'" Silvestre remembered. "Ronaldo just had a big smile, but now he's won it four times, and it all started for him with that friendly in Lisbon all those years ago."